Television apparatus



0. E. WAGENKNECHT April 14, 1953 TELEVISION APPARATUS 3 Sheets-Sheet 1 Filed Feb. 8, 1951 F/gZ CLEAR BLUE CLEAR OTTO E. WAGENKNECHT H/S' ATTORNEY Patented Apr. 14, 1953 TELEVISION APPARATUS Otto E. Wagenknecht, Chicago, Ill.,

assignor to Zenith Radio Corporation, a corporation of Illinois Application February 8, 1951, Serial No. 210,020

11 Claims. 1

This invention relates to television'apparatus for use in monochrome television systems having prescribed line and field frequency specifications, and at the same time, useful for color-television systems having scanning frequencies that may be the same as, or diiferent from, those of the monochrome systems. More particularly, the invention relates to television apparatus which may utilize a monochrone television signal, and which may be quickly and conveniently conditioned to utilize a color-television signal having the same or distinctly different transmission standards.

In accordance with present-day standards, monochrome television signalsare transmitted with scanning frequencies of 30 frames or 60 interlaced fields per second with 525 lines in each field. It has been proposed that the color-television signals transmitted in the field-sequential system have synchronizing frequencies comprising 24 frames or 48 interlaced color fields per sec-- ond, each of the color fields representing one of three primary colors of the televised image. It is also proposed that each primary color field be composed of 405 lines.

Since it is contemplated that monochrome and color-television broadcasts will be concurrently available, it is most desirable to provide a commercially acceptable television receiver capable of utilizing the monochrome signals to produce black and white images, and also capable of using the color signals to produce images in natural color. Because of the possible use of different standards for the monochrome and color television signals, serious problems have arisen concerning the production of such a television receiver.

The present invention provides improved apparatus that may be constructed in a relatively simple and efiicient manner to utilize television signals of various synchronizing-frequency composition in the reproduction of images in natural color or in black and white. The apparatus comprises a cathode-ray video-signal translating device, which includes a sensitized screen and means for scanning an electron beam developed within the device over an area of the screen in a series of fields of parallel lines. A color-filter drum, having a plurality of different color-filter segments 7 disposed on the peripheral surface thereof and a plurality of clear segments interspersed with the color-filter segments, is rotatablysupported so that it encircles at least a portion of the translating device with the segments traversing an optical path to the screen. A driving mechanism is provided for rotating the drum at such a speed that alternate segments of the drum traverse the scanned area of the screen in coincidence with successive field scansions thereof by the beam. The apparatus further includes means for adjusting the relative phase of the drum and the field scansions between a first condition. wherein the color-filter segmentstraverse the screen in coincidence with successive field scansions thereof for color reproduction, and a second condition wherein the clear segments traverse the area in coincidence with succeeding field scansions for black and white reproduction- It is, accordingly, an object of this invention to provide improved television apparatus for use in color or monochrome television systems.

A further object of this invention is to provide improved television apparatus for use in a television system and capable of reproducing either black and white images or, when so. desired, images in natural color.

Another object of this invention is to provide improved television apparatus which may utilize a monochrome television signal for the reproduction of black and white images, and which may further utilize a color-television signal for the reproduction of images in natural color.

Yet a further object of the invention is to provide improved television apparatus which may utilize a monochrome television signal of certain prescribed synchronizing standards for the reproduction of black and white images, and which may be conditioned in a simple and expedient fashion to utilize color-television signals of distinctly diiferent synchronizing standards for the reproduction of images in natural color.

The features of this invention which are believed to be new are set forth with particularity in the appended claims. The invention itself, however, together with further objects and advantage thereof may best be understood by reference to the following description when taken in conjunction with the accompanying drawings, in which:

Figure 1 represents a rear view of a television receiver constructed in accordance with one embodiment of the invention,

Figure 2 is a sectional view of the receiver taken along the lines 2-2 of Figure 1,

Figures 3 and 4 are diagrams indicatingan operating principle of the invention,

Figure 5 is a block diagram of a television receiver utilizing the embodiment of the invention shown in Figures 1 and 2, and,

Figure 6 is a block diagram of a television receiver utilizing a second embodiment of the invention.

The television receiver illustrated in Figures 1- and 2 comprises a cabinet H) which includes a shelf ll supporting the chassis 12 of the receiver. A cathode-ray video-signal translating device or image-reproducing tube I3 is supported from the side 14 of cabinet in by means of a strap is extending around the rim of the face of the tube, and by a bracket 16 enclosing a usual deflection yoke I1 mounted on the neck of the tube. Various electrical connections, not shown, extend from chassis II! to reproducing tube l3.

erse the optical path from the screen IQ of device I3 to an observer. A trim bezel 20 is provided to define the optical path to the observer, and a face plate 2| is supported on cabinet In adjacent the trim bezel by means of a bezel ring 22. A speaker 23 is mounted within the cabinet, as shown, and is electrically connected to the receiver chassis in well-known manner to reproduce the sound components of received television signals.-

Drum' I8 is supported on a shaft 24, which is coupled to afurther shaft 25 through a flexible coupling 26. Shaft 25 is rotatably supported by means of bearings 29 and 30 between the side wall 21 of cabinet I and a plate 28. Plate 28 acts as a support for bearing 30 and is itself supported on a pair of blocks 31, 32 by means of" shock mounts 33 and 34. Shaft 24 is supported by a bearing 35 secured to a plate 35 mounted on plate 28 by a pair of shock mounts 31, 38.

A synchronous motor 39 is rotatably supported by plate 28 and may be rotated by a shaft 4!! coupled thereto through pinions 4|, 42, which are aflixed respectively to shaft 40 and to the casing of motor 39. A pulley wheel 43 of a preselected diameter and a pulley Wheel 44 of another preselected diameter are' rotatably mounted on shaft 25 and are driven by motor 39 through rubber cog belts 45, 46. The pulleys 43 and. 44 may be selectively coupled to shaft 25 by a wellknown cone clutch arrangement 47 having a member which is keyed to shaft 25 and displaceable therealong for selective engagement with the pulleys.

The arrangement of the color-filter and clear segments of drum I8 is best shown in Figures 3 and 4. It is assumed that the apparatus is to be used for color reproduction in a field-sequential color system utilizing the three primary colors red, blue and green. Each segment of the drum is arranged preferably to have a field dimension that is less than half the field dimension of the scanned area of the cathoderay tube. In other words, the projected height of any segment on the face of the cathode-ray tube is less than one-half the screen height of the tube. The color-filter segments alternate with the clear segments, and are arranged in a repeating color sequence of green, red and blue. The several segments may be separated by narrow, transverse opaque surfaces to reduce reflection from the face of the drum. The drum may be composed of a transparent plastic having various segments colored with the primary colors and other segments left clear. Alternatlvely, the drum may comprise metallic framework with the various color-filter segments affixed thereto and with the intervening peripheral sections left open or the clear sections of the drum may be composed of an opaque mesh with a high percentage of open area.

To condition the receiver for the reception and utilization of a color-television signal having prescribed synchronizing frequencies, cone clutch 41 is shifted to engage shaft 25 with pulley 4d. The diameter of pulley 44 is so chosen in relation to the speed of motor 39 andthe fieldscanning frequency of the received television signal that alternate segments of the drum traverse or pass in front of the scanned area of tube I3 in-coincidence'with successive field scansions thereof by the cathode-ray beam. Shaft 40 is rotated, if necessary, to adjust the phase relation of thedrum relative to the field scansions of tube I5 so that succeeding color-filter segments traverse the scanned 'area in coincidence With succeeding field scansions thereof and with proper color phasing with respect to the sequentially received color fields of the color-television signal.

While there are a variety of speeds for the drum to eifect image reproduction in natural color, a simple and illustrative example is as follows. Assume the phasing to be such that at the instant the electron beam is at the top of' screen l9 at the start of its trace of a red-color field of the received signal, the mid-portion of a red color filter .of the drum is aligned with the beam. If the peripheral drum speed is approximately equal to the field rate of the received signal, this relationship is maintained throughout the red-field scansion of the beam and thered color field is traced on the screen. At the completion of that field trace, the beam returns to its starting point at which-time the succeeding blue color filter assumes theposition which the red filter occupied at the start of the red field. This follows in view of the afore-described size of the drum segments and from the fact that a clear segment is interposed between the red and blue color filters. Consequently, during the next field trace in which the beam is modulated in accordance with the blue information of the received signal, a blue color field is traced on screen I9. In like manner, the third field scansion results in the tracing of a green color field onscreen I9- So long as the field rate of the transmitted signal is suificiently high, the eye of the observer integrates the several color fields of the image, giving the observer a sensation of image reproduction in natural color.

To condition the receiver for the reception and utilization of a monochrome television signal having different synchronizing standards from the color signal, cone clutch 41 is shifted to engage pulley 43 with shaft 25. The diameter of pulley 43 is so chosen that the drum is rotated at a speed related to the field-scanningfrequency. of the monochrome television signal so that alternate segments of the drum'again traverse the scanned area of the screen in coincidence with successive field scansions thereof by,

the cathode-ray beam. For the reception of the monochrome signal, shaft id-is rotated to adjust the phasing of the drum so that the clear segments cooperate with the electron beam as it scans screen I9 during successive field scansions to reproduce black and white images.

Cone clutch 4! is, preferably, coupled to an electrical switching mechanism so that'actuation of the clutch not only alters the drum speed to correspond with the different synchronizing standards of the monochrome and color television signals, but also switches the receiver scanning system so that the lineand field-scanning rates of reproducing device l3 may be modified similarly to correspond with these difierent standards.

Therefore, by merely shifting cone clutch 41 to a first condition and adjusting shaft 40, the receivermay be conditioned .to utilize a monochrome televisionsignal and reproduce a black and white image. Alternately, by shifting the cone clutch to a second condition and adjusting assuage shaft 40, the receiver may be conditioned to utilize a color-television signal and reproduce images in natural color. It is apparent that screen I9 must be composed of a fluorescent substance having a relatively short persistence of luminescence to avoid any carry-over from the color filters to the clear segments andvice versa.

The television receiver of Figure comprises a radio-frequency amplifier 50 of one or more stages having input terminals connected to a suitable antenna circuit 5I, 52 and output terminals connected to a first detector 53. First detector 53 is coupled to an intermediate-frequency amplifier 54 of any desired number of stages, and the output terminals of amplifier 54 are connected to a second detector 55. Second detector 55 is connected through a video amplifier 56, of one or more stages, to the input electrodes of cathode-ray image-reproducing tube I3. The sound portion of the receiver has not been shown because it constitutes no part of the present invention and it may be of any conventional construction. Y

Second detector 55 is further connected to a synchronizing-signal separator 51 which, in turn, is connected to a field-sweep system 58 and a line-sweep system '59. The systems are connected to a deflection yoke 60 associated with reproducing tube I3, and arranged to scan the electron beam thereof over an area of screen I9 in a series of fields of parallel lines. The sweep systems 58, 59 are so constructed that they may be switched between: (a) a first condition wherein they may be synchronized by a received monochrome television signal so that screen I9 is scanned by the beam at a line and field rate corresponding to the synchronizing standards of the monochrome signal; and (b) a second condition wherein the sweep systems may be synchronized by a received color-television signal so that the screen is scanned in accordance with the synchronizing standards of the color signal. Synchronous motor 39 is rotated at a preselected speed by means of a motor-energizing source 6|. Radio-frequency amplifier 50 may be tuned to amplify a monochrome television signal intercepted by antenna circuit 5I, 52. This signal is heterodyned to the selected intermediate frequency of the receiver in first detector 53 and the. resulting intermediate-frequency signal is amplified in intermediate-frequency amplifier 54. The amplified intermediate-frequency signal is detected in second detector 55 to produce a composite video signal. The video signal is amplified in amplifier 55 and applied to the input electrodes of reproducing device I3 to control the intensity of the cathode-ray beam developed therein in well-known manner.

The synchronizing components of the composite video signal are separated in synchronizingsignal separator 51 and used to control the operation of sweep systems 58, 59 which, in turn, control the fieldand line-scansion of the cathoderay beam in device I3. Cone clutch 41 is shifted so that drum I8 is rotated by motor 39 at a speed related to the field-scanning frequency of the monochrome signal so that alternate segments of the drum traverse the scanned area of the screen in coincidence with successive field scansions thereof by the cathode-ray beam. As previously stated, clutch 41 may be coupled, as shown by dotted lines 62 to switching devices in sweep systems 58, 59 to condition the sweep systems for synchronization in accordance with the.

synchronizing components of, the monochrome signal when in its above-described condition.

Synchronous motor 39 may be rotated by shaft 40 of Figure l to adjust the phase of the color drum so that the clear segments of the color drum traverse the scanned area of screen I9 in coincidence and alignment with the successive field scansions thereof so that the receiver reproduces a black and white image.

Alternatively, cone clutch 41 may be shifted to rotate color drum I8 at a speed corresponding to the field-scanning frequency of a received color-television signal, and sweep systems 58, 59 simultaneously conditioned for synchronization by its synchornizing components. Radio-frequency amplifier 50 may be tuned to amplify the received color-television signal and the receiver utilizes this signal in the same manner as it utilizes the monochrome signal. Synchronous motor 39 is rotated by shaft 40 of Figure 1 to adjust the phase of the color drum so that the colorfilter segments traverse the scanned area of screen I9 in coincidence and alignment with successive field scansions thereof so that the receiver reproduces images in natural color.

The receiver of Figure 6 is similar to the aforedescribed receiver, except that the conditioning from black and white to color reception is performed electrically instead of mechanically. Stages of the receiver of Figure 6 which correspond to stages of the receiver of Figure 5 have been indicated by like numerals. As shown in Figure 3, color drum I8 is provided with two groups of red, green and blue color segments. When this drum is used in conjunction with the receiver of Figure 6, a soft iron projection I00 is mounted on the drum adjacent one of the red segments, and a soft iron projection IOI is mounted adjacent the other red segment. An iron core I02 having extremities which define an air gap is mounted adjacent the color drum so that projections I00, IOI pass through the air gap as the drum rotates. A coil I03 is wound about core I02 and connected to a phase detector and control circuit III by way of leads I04. An energizing source is included in the phase detector so that a current flows through coil I03. As the projections pass through the air gap of core I02, they vary the magnetic reluctance of the magnetic circuit of the core and cause pulses to be developed in leads I04. Due to the positioning of segments I00, IOI each pulse developed on leads I04 indicates the initiation of a traversal of screen I9 by one of the red segments.

In the receiver of Figure 6, synchronous motor I05 for driving the drum is a condenser type induction motor and is connected to a motor-energizing source I06 through a winding I0'I of a saturable transformer I08. Second detector 55 is connected to a color synchronizing-signal separator I09 which, in turn, is connected through a double-pole double-throw switch III] to phase detector and control unit I I I. The output terminals of unit I II are connected to a second winding I I2 of saturable transformer I08. Synchronizing-signal separator 51 is connected to a frequency divider H3 and applies field synchronizing pulses thereto wherein they are divided at the rate of 3:1. The output terminals of frequency divider II3 are connected to a phase shifter II4, whose phase-shifting characteristic may be varied as shown by the phase-adjuster H5. The output terminals of phase shifter II4 are connected through switch IIO to unit III. SwitchIID is coupled as shown by dotted lines II5 to switching devices in sweep systems 58, 59

swam-142:

so that-when switch I It connects separator-:- I09 to unit' III the'sweep systems are conditioned" for synchronization in accordance with the syn-@- chronizing components of a color television sig-. nal; and whenthe switch is in a positionto connect-phase shifter-I M to unit I1 I, the sweepsysa terms are in a condition'for synchronization bythe synchronizing components of a monochrome television signal.

To *conditiori thereceiver fortheutilization of r a color television signal intercepted by antenna The color-televisionsignal will be assumedto include a color-synchronizing component which precedes each sequence ofred, green and blue color fields: The colon-synchronizing compo"- :nents are derived separator I09 and applied to phase detector and controlunit IH. components are'compared in unit- II with the pulses applied thereto over leads I04, and the unitdevelops a control current in winding III of :saturable transformer I08." Variations the controlcur'ren't cause corresponding variations'in the saturation of the core of transformer I 08 which, in turn, varies'theimpedance-of winding I01 to control the speed of motor I05; Any alteration in phase between the pulses from separator IDS-and the pulsesfrom leads I94 causes an alteration in thecontrol currentindicative In this manner, the

of such phase alteration. speed of motor I05'and, hence, the speed of color drum I8 may be synchronized with the color-' television signal so that, the segments of the segment, the drum= is automatically phased so that the color filters traverse the screenin coin cidence with corresponding color fields of the re-' ceived signal, enabling the receiver to reproduce natural color images. The above-describedcom trol arrangement for synchronizing thephase and speed of a color disc or drum with a-received color-television signal is well known, and further description thereof is deemed to be unnecessary;

To condition the receiver for the utilization of a monochrome television signal, switch III! is placed in its upper position to connect phase shifter H4 to unit III; and simultaneously'to condition sweep systems 58, 59 for synchronization with the synchronizing components of-the received monochrome-signal. The-television sig nal is amplified and detected by the receiver in the previously-described manner, its video components being utilized to. control the intensity of the cathode-ray beam in device It and: its

synchronizing components being-utilized to con.-- trol the scansions of thebeam;

The field-synchronizing components of the television signal are frequency divided in divider .I I3, and the divider. produces-la pulse "indicating Radio-fre These the :zinitiation' aof T every third, field of the *televi These pulses are passed through sion' signal. phase-shifter H4-to phase detector III wherein they arecomparedwith the pulses onleads I04.

As previously. described, the pulses on leads I04 occur during the initiation of each red segment of thezc'color drum, that-is, they occur once in every traversal of screen I9'v by three-clear segments.

each'group of three fields of the television signal and each group of three clear segments of drum Ill; Thecomparison of these pulses produces a control current in winding II2- to adjust the speed of motor I05 so that the segments on drum l8 trave'rse' screen I9'at the same rate as the field scansion of the screen by the cathoderay beam. Phase adjustor ll5may be manipulated to eifect a phase relationbetweenthe-fre-' quency-divided pulses applied to phase detector- I I I and thefields of the received't'elevision signal such that the clear segments of'drum l8 traverse While" particular embodiments of theinvention have been shownand described, modifications may bemade andit is intended'in the appended claims to cover all such modifications as fall within the true-spirit and'scope of the'invention.

I claim:

1". Television apparatus comprising: a sensitized screen; means'for developing an electron beam and for directing said beam to said screen; means for recurrently'scann'ing said beam over an area of said'screen in a series of fields of parallel'lines; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral surface thereof and a plurality of clear segments interspersed with said color'filter segments; means for rotatably supportingv said drum so that the segments traverse" an optical pathto the screen; a driving mechanism for rotating said drum at such a speed that alternate segments of saiddrum traverse said area of said screen in coincidence with successive field scansions thereof by said beam; and means for adjusting the relative phase of said drum and said field scansions between a first condition wherein said 'color-filter segments traverse said area in coincidence with successive field scansions thereof, and asecond condition wherein said clear segments traversev said area in coincidence with successive field scansions thereof.

2; Television apparatus comprising: a cathoderay video-signal translating device including a sensitized screen and means for scanning an electronbeam developed therein over an area of said screen in al series of fields of parallel lines; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral surface thereof and a-plurality of clear segments interspersed, with said color-filter segments; meansforrotatably supporting said drum so that itencircles-at least a portion of said device with-said segments traversing an optical path Therefore, the pulses compared in the phase detector of'unit' IIIrepresent respectively to said screen; a driving mechanism'for rotating said drum at such a speed that alternate segments of said drum traverse said area of said screen in coincidence with successive field scansions thereof by said beam; and means for adjusting the relative phase of said drum and said field scansions between a first condition wherein said color-filter segments traverse said area in coincidence with successive field scansions thereof, and a second condition wherein said clear segments traverse said area in coincidence with successive field scansions thereof.

3. Television apparatus comprising: a cathoderay video-signal translating device including a sensitized screen and means for scanning an electron beam developed therein over an area of said screen in a series of fields of parallel lines; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral surface thereof and a plurality of clear segments interspersed with said color-filter segments; means for rotatably supporting said drum so that it encircles at least a portion of said device with said segments traversing an optical path to said screen; a driving mechanism for rotating said drum at such a speed that alternate segments of said drum traverse said area of said screen in coincidence with successive field scansions thereof by said beam; and mechanical means coupled to said driving mechanism for adjusting the relative phase of said drum and said driving mechanism between a first condition wherein said color-filter segments traverse said area in coincidence with successive field scansions thereof, and a second condition wherein said clear segments traverse said area in coincidence with successive field scansions thereof.

4. Television apparatus comprising: a cathode-ray video-signal translating device including a sensitized screen and means for scanning an electron beam developed therein over an area of said screen in a series of fields of parallel lines; a color-filter drum having a plurality of difierent color-filter segments each having a field dimension not exceeding one-half the field dimension of said area of said screen disposed o the peripheral surface thereof, and a plurality of clear segments each having a field dimension substantially equal to the field dimension of each of said color segments and interspersed with said color-filter segments; means for rotatably supporting said drum so that it encircles at least a portion of said device with said segments trav ersing an optical path to said screen; a driving mechanism 'for rotating said drum at such a speed that alternate segments of said drum traverse said area of said screen in coincidence with successive field scansions thereof b 'said beam; and means for adjusting the relative phase of said drum and said field scansions between a first condition wherein said color-filter segments traverse said area in coincidence with successive field scansions thereof, and a second condition wherein said clear segments traverse said area in coincidence with successive field scansions thereof.

5. A television receiver comprising: a cathoderay image-reproducing device including a, fluorescent screen and elements for scanning an electron beam developed therein over an area of said screen in a series of fields of parallel lines; I

a scanning system coupled to said elements for effecting scansion of said beam over said area at a preselected field-scanning rate; a colorfilter drum hav ng a phi al y of dif erent colorfilter segments disposed on the peripheral surface thereof and a plurality of clear segments interspersed with said color-filter segments; means for rotatably supporting said drum so that it encircles at least a portion of said device with said segments traversing an optical path from said screen; a driving mechanism for rotating said drum; 3, speed-control devic coupled to said driving mechanism to synchronize the rotation of said drum with said preselected field-scanning rat so that alternate segments of said drum traverse said area of said screen in coincidence with successive field scansions thereof by said beam; and means for adjusting the relative phase of said drum and said field scansions between a first condition wherein said color-filter segments traverse said area in coincidence with successive field scansions thereof. and a second condition wherein said clear se ments traverse said area in coincidence with successive field scansions thereof.

6. A television receiver comprising: a cathode-ray image-reproducing device including a fluorescent screen and elements for scanning an electron beam developed therein over an area of said screen in a series of fields of parallel lines; a scanning system coupled to said elements for selectively effecting scansion of said beam over said area at a plurality of predetermined field-scanning rates; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral surface thereof and a plurality of clear se ments interspersed with said color-filter segments; means for rotatably supporting said drum so that it encircles at least a portion of said device with said segments traversing an optical path from said screen; a driving mechanism for rotating said drum; a speed-control device coupled to said driving mechanism for selectively adjusting the rotation of said drum between a plurality of predetermined speeds corresponding respectivel to said plurality of field-scanning rates so that alternate segments of said drum traverse said area of said screen in coincidence with successive field scansions thereof by said beam; and means for adiusting the relative phase of said drum and said field scansions between a first condition wherein said color-filter segments traverse said area in coincidence with successive field scansions thereof, and a second condition wherein said clear segments traverse said area in coincidence with successive field scansions thereof.

7. A television receiver comprising: a cathode-ray image-reproducing device including a fluorescent screen and elements for scannin an electron beam developed therein over an area of said screen in a series of fields of parallel lines;

a scanning system coupled to said elements for selectively effecting scansion of said beam over said area at first and second field-scanning rates; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral surface thereof and a plurality of clear segments interspersed with said color-filter segments: means for rotatably supporting said drum so that it encircles at least a portion of said device with said segments traversing an optical path from said screen; a, driving mechanism for rotating said drum; a speed-control device coupled to said driving mechanism for selectively adjusting the rotation of said drum between a pair of predetermined speeds corresponding respectively to said first and second field-scannin rates so that alternate segments of said drum traverse said-area of said screen in coincidence with successive field scansions thereof .by :Jsaid beam; and means for "adjusting the .relative phase of said :drum and said "field scansionlrbetween a first condition wherein'sai'd color-filter segments traverse said-area in coincidence-with successive field scansions thereof, :and a second condition wherein said clear segments traverse said area in coincidence with successive field scansions thereof.

8. A television receiver comprising:=-a'cathoderay image-reproducing device including afiuorescent screen and'elements'for scanning anelectron beam developed thereinoveran 'areaof" said screen in a series of fields 'ofparallel'lines; "a

scanning system coupled to said elements "for selectively efiecting scansion of "said beam rover said area at first and second-field scanning; rates;

a color-filter drum having-a plurality :Qfdifierent color-filter segments disposed on therperipheral surface thereof and'a plurality of clear:segments interspersed with said color filter asegments;

means for rotatably'supporting said 'drumaso. that it encircles at least a portion ofrsaiddevicewith said segments traversing an optical pathffmm said screen; a-driving motor; a.pairzof beltzdrives extending fromsaid motor to said .drumifor rotating said drum at speeds corresponding respectively to said first and second field-scanningratespa clutch mechanism for selectively couplingqsaid belt drives to said drum so that'alternateesegments of said drumtraverse said sareaofssaid screen in coincidence with successiveffieldv scansions thereofby said beam; .and'means for .adjusting the relative phase'ofi'said:drum'and-said field scansion between :a first condition wherein said color-filter segmentstraversesaid 'area'in coincidence with successive field scansionsthereof, and a second condition wherein-saidclearsegments traverse saidarea inconcidencerwi-thsuccessive field scansions thereof.

9. A television'receiver comprising: a-cathoderay image-reproducing device including a fluorescent screen and elementsfor scanning an-electron beam developed therein over an-area of said screen in a series of fields of parallel lines; .a scanning system coupled to 'said qelements for selectively effecting .scansion of. said beam over said'area at first and secondfield-scanning rates; a color filter drum having aplurality of different color filter segments disposed on the peripheral surface thereof and, a plurality. of .clearsegments interspersed with said color filter segments; means for rotatably supporting said drumso that itencircles at f least a portion of said device .with said segments traversing an. optical path .from

said :screen; a .driving .mechanism .;for ...rotating .-;said drum; :3, 'speed-control device coupledto-said driving "mechanism .for selectively adjusting the rotationof said drum between-apair of ..pr.edetermined speeds corresponding. respectively ,to said first and second field-scanning rates so that alxternate segments of said drum traverse saidiarea of said screenin coincidence with successivei field :scansions thereof by :saidv beam; .and. means for controlling the. relative phase .of v.said 'drum and :said field scansions so that. said .colorfilterisegments traverse said area. in coincidence with. successive. field scansions .thereof at said .first fieldscanning rate whilesaid clearsegments :traverse said area .in coincidence with successive :field scansions thereof .at said second. fiitld fi d l l rate.

12 '-;1'0.,-A television receiver comprising: :a cathode-ray image=reproducing device including a "fluorescentscreen'and elements for scanningan 'electrontbeamtdeveloped therein over anarea of said screen in a series of fields of parallel lines; a

scanning system coupled to said elements for selectively effecting scansion of said beam over *saidsareaat first and second field-scanning rates; a'color filter drum having'a plurality of different color-filtersegments disposed .on the peripheral a" surface thereof and asplurality of clear segments interspersed with said .color filter segments; "means forgrotatably.supporting said drum so that it encircles :at least .aportion of .said device with :said :segments :traversing .an optical path from said screen; .a drivingmechanism for rotating :said drum;.'a speedecontroljdevice coupled to said drivingqmechanismfor selectively adjusting the rotation. ofsaiddrum between-apair of predeterixmined :speeds :corresponding respectively to said -ifirst'and second field-scanning rates so that alter- ;natersegmentsOfsaid'drum traverse said area of :said screen in coincidence with successive field :scansionsrthereofby said'beam; and mechanical ;means coupled'to said driving mechanism for adjustingithe relative-phase of saiddrum and said driving mechanism between a first condition :wherein said color filter segments traverse said area in coincidence with successive field scansions vthereof, and a second condition wherein .-;said:clear'segments traversesaid area in coinci- .c dence with successive. field. scansions thereof.

311. A television receiver .comprising: a cathodeeray "image-reproducing device including a fluorescentscreenand elements for scanning an electron beamdeveloped therein over an area of said screenin a'seriesof fields of parallel lines; t-as-lscanningsystem coupled to said elements for .selectivelyeffecting. scansion of said beam over :rsaid areaat a plurality of predetermined field- :scanning rates; a color-filter drum having a plurality of different color-filter segments disposed on the peripheral'surface thereof and a plurality of clear segments interspersed with said :colo-nfilterasegments; means for rotatably supzportingsaid drum so that it encircles at least a yportion of said devicewith said, segmentstravers- .ing-an optical path from said. screen; .a driving umechanism for rotatingsaid drum; a speed-control device coupled to said driving mechanism and to-said scanning. systemfor selectively adjusting the rotation of. said drum betweena plurality of predetermined ,speeds and for simultaneously --selectivelyradjusting.said scanning systemto said plurality of. field-scanning rates, so that alternate asegments of .said drum traversesaid area .of said screenin. coincidence with successivefield scan- 7 azsions-qthereof by said beam; and means for ad- Jjustingthe relative phase of said drum and said field ,scansionsbetween. a .first condition wherein :-said color-filter segments traverse said area in 1coincidencewith successive. field-scansions thereof,.and a second condition wherein said clear seg- .ments traverse said area in coincidence with sucicessive. fieldscansions thereof.

OTTO E. WAGENKNECHT.

".fRe'ferences Cited fin the-file of "this "patent U NITED STATES -PA'ITENTS 

